Three varieties of Harmonic Percolator by Fredric Effects (www.fredric.co.uk Black: How blue, with Wima audio-grade capacitors, precision metal film resistors, switchable noise reduction circuitry Blue: Vintage NOS right 2N404 (A) & 2N3565 transistors, 1N695 Germanium diodes Beige: NOS Russian Standard & MP16B Ge Si transistors 2N3904, Russian KD514A silicon diodes
http://www.youtube.com/watch?v=hZOEY_cubPY&hl=en
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